Who developed the first digital computer to use both electrical and mechanical devices?

The first digital computer to utilize both electrical and mechanical devices was developed by Howard Aiken. His groundbreaking work on the Harvard Mark I, also known as the IBM Automatic Sequence Controlled Calculator (ASCC), began in the 1930s. The machine was notable for its use of electromechanical relays and was one of the earliest programmable computers. Aiken's design combined the speed of electrical operations with the reliability of mechanical components, making it a significant advancement in the field of computing.

His collaboration with IBM played a crucial role in transitioning from purely mechanical computing devices to mixed systems that incorporated both electrical and mechanical technologies. This development was instrumental in paving the way for further advancements in digital computing.